As power consumption of a processor is becoming an important aspect of processor performance, inactive circuits in the processor are turned off to save power consumption of the processor. Inactive digital circuits can be easily turned off by setting the signals to the transistor gates of such circuits to levels that cause the transistors of the digital circuits to be off. These digital circuits can be quickly turned on by simply setting the signals to the transistors gates of such circuits to levels above the transistor threshold voltage levels.
Conversely, analog circuits are generally turned off when such analog circuits are not required to wake-up or be in an operational state quickly. Turning on an analog circuit is a long process because analog bias signals of an analog circuit take a longer time to setup to their designed bias levels compared to turning on a digital circuit. For example, digital circuits can wake-up from an inactive state (e.g., power-down state) to an active state (e.g., power-up state) in a matter of picoseconds or less, while analog circuits may take several hundred nanoseconds to wake-up from an inactive state (e.g., power-down state) to an active state (e.g., power-up state). Longer wake-up time of analog bias signals compared to digital signals may reduce overall processor performance despite the power savings realized from turning off the analog circuit when the analog circuit is inactive.